Frangible gas turbine engine airfoil with fusion cavities

Abstract

An airfoil defining a span extending between a root and a tip and a chord at each point along the span extending between a leading edge and a trailing edge. The airfoil includes a frangible airfoil portion at the tip extending between the leading edge and the trailing edge and extending between the tip and a frangible line along the span. The frangible airfoil portion includes an exterior surface. The exterior surface at least partially defines at least one fusion cavity at least partially defining the frangible line. The airfoil further includes a residual airfoil portion extending from the frangible line to the root along the span. The residual airfoil portion meets the frangible airfoil portion at the frangible line. As such, the frangible airfoil portion deforms or partially or fully detaches relative to the residual airfoil portion at the frangible line following an event creating imbalance.

What is claimed is: 
     
       1. An airfoil defining a span extending between a root and a tip and a chord at each point along the span extending between a leading edge and a trailing edge, the airfoil comprising:
 a frangible airfoil portion at the tip extending between the leading edge and the trailing edge and extending between the tip and a frangible line along the span, the frangible airfoil portion including an exterior surface, wherein the exterior surface at least partially defines at least one fusion cavity, with a portion of the at least one fusion cavity closest the root at least partially defining the frangible line; and 
 a residual airfoil portion extending from the frangible line to the root along the span, wherein the residual airfoil portion meets the frangible airfoil portion at the frangible line, the frangible line defining a point of detachment of the frangible airfoil portion during a failure mode of the airfoil; 
 wherein the at least one fusion cavity comprises at least one fusion hole extending from the tip at least partially along the span to the frangible line. 
 
     
     
       2. The airfoil of  claim 1 , wherein the airfoil is formed at least in part from a composite material. 
     
     
       3. The airfoil of  claim 1 , wherein the airfoil is a fan blade of a gas turbine engine. 
     
     
       4. The airfoil of  claim 1 , further comprising a filler material positioned within the at least one fusion cavity, at least partially filling the at least one fusion cavity. 
     
     
       5. The airfoil of  claim 1 , wherein the at least one fusion hole comprises a plurality of fusion holes, and wherein at least one fusion hole of the plurality of fusion holes extends between the tip and the frangible line. 
     
     
       6. The airfoil of  claim 5 , wherein the plurality of fusion holes each extends between the tip and the frangible line. 
     
     
       7. The airfoil of  claim 1 , wherein the at least one fusion hole extends along at least 5% of the span but less than 25% of the span. 
     
     
       8. The airfoil of  claim 1 , wherein the at least one fusion hole extends parallel to the span. 
     
     
       9. The airfoil of  claim 1 , wherein the airfoil further defines a pressure side and a suction side, and wherein the at least one fusion hole extends at least partially along the chord, at least partially toward one of the pressure or suction side, or at least partially along the chord and at least partially toward one of the pressure or suction side. 
     
     
       10. The airfoil of  claim 1 , wherein the at least one fusion cavity comprises at least one fusion channel extending from the tip to the frangible line. 
     
     
       11. The airfoil of  claim 10 , wherein the airfoil further defines a thickness extending between a pressure side and a suction side, and wherein the at least one fusion channel defines a thickness reduction of at least 10% of the thickness but less than 80% of the thickness. 
     
     
       12. The airfoil of  claim 11 , wherein the at least one fusion channel defines a variable thickness reduction. 
     
     
       13. The airfoil of  claim 1 , wherein at least one of the frangible airfoil portion or the residual airfoil portion includes a first material defining a first modulus of elasticity, the airfoil further comprising:
 a filler material positioned within the at least one fusion cavity, at least partially filling the at least one fusion cavity, wherein the filler material includes a second modulus of elasticity less than the first modulus of elasticity. 
 
     
     
       14. An airfoil defining a span extending between a root and a tip and a chord at each point along the span extending between a leading edge and a trailing edge, the airfoil comprising:
 a frangible airfoil portion at the tip extending between the leading edge and the trailing edge and extending between the tip and a frangible line along the span, the frangible airfoil portion including an exterior surface, wherein the exterior surface at least partially defines at least one fusion cavity, with a portion of the at least one fusion cavity closest the root at least partially defining the frangible line; and 
 a residual airfoil portion extending from the frangible line to the root along the span, wherein the residual airfoil portion meets the frangible airfoil portion at the frangible line, the frangible line defining a point of detachment of the frangible airfoil portion during a failure mode of the airfoil; 
 wherein the at least one fusion cavity comprises at least one fusion channel, wherein the at least one fusion channel comprises a first fusion channel extending at least partially along the frangible line, and a second fusion channel extending along the exterior surface of the frangible airfoil portion. 
 
     
     
       15. The airfoil of  claim 14 , wherein the at least one fusion channel extends along the chord at a point along the span at least 10% but less than 50% of the span from the tip. 
     
     
       16. The airfoil of  claim 14 , wherein the first fusion channel extends along a full length of the frangible line. 
     
     
       17. The airfoil of  claim 14 , wherein the first fusion channel extends along at least 10% of the chord at a point along the span of the frangible line but less than the full chord at the point along the span of the frangible line. 
     
     
       18. The airfoil of  claim 14 , further comprising a filler material positioned within the at least one fusion cavity, at least partially filling the at least one fusion cavity. 
     
     
       19. The airfoil of  claim 14 , wherein the second fusion channel extends at least partially along the frangible line. 
     
     
       20. The airfoil of  claim 14 , wherein the second fusion channel extends at least partially along the chord at a point along the span between the frangible line and the tip.